Jeep Garage  - Jeep Forum banner

1 - 20 of 37 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter #1 (Edited)
Any of you are using unleaded regular 87 octane on the V8?

Or should I use only 89 octane?

I know that the spec says it is acceptable 87 and 89 is recommended ... but what are the implications ???

Thanks:thumbsup:
 

·
Registered
Joined
·
941 Posts
Slightly less hp are the implications. The vehicle is smart enough to sense that it has 87 in it, and will pulling timing back to compensate. This yields a slight (15ish?) loss in hp.

People will tell you that its better to use 89 long term for a variety of (mostly bogus) reasons. Keep in mind, the Hemi is also a work truck engine, and can run for hundreds of thousands of miles on 87.

Sometimes I feel like I get slightly better fuel economy using 89. It may be a psychological thing though.
 

·
Super Moderator
Joined
·
9,315 Posts
While I'm driving a MY12, the specifications are the same. I run 87. The place I buy most of my gas (Costco) doesn't even sell 89. I've not had any performance issues and get good fuel economy.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #5
Thanks for sharing!!!

Nice to know that you guys had no problems using 87 octane! That's what I'm planning to do!

:thumbsup:
 

·
Registered
Joined
·
122 Posts
I definitely do get better mpg's with 89, between 1 and 2 more mpg's when using 89. I only do Shell and at least here in southeast Ontario 87 has up to 10% ethanol, 89 up to 5% ethanol, and 91 0% ethanol. I guess the difference has to do with the ethanol %.
 

·
Super Moderator
Joined
·
9,315 Posts
That makes sense, nvfusa...Ethanol unfortunately lowers fuel economy. I don't know what the blend is around here as the pumps just have stickers that say "up to 10% Ethanol" on them.
 

·
Premium Member
2017 Summit
Joined
·
8,842 Posts
I bought gas for my Jeep for the first time today. I was happy buying 89 for my Hemi, coming from a vehicle that needed 93.

Using 87 won't hurt anything, but the computer will retard the timing to prevent pinging. This will reduce performance and mileage. Whether it's a noticeable amount is any body's guess.
 

·
Registered
Joined
·
94 Posts
While I'm driving a MY12, the specifications are the same. I run 87. The place I buy most of my gas (Costco) doesn't even sell 89. I've not had any performance issues and get good fuel economy.
I also fuel at Costco, will it hurt the engine if I only use 91 octane? I have a 2014 Hemi, and will be fueling today for the first time

Thanks
 

·
Registered
Joined
·
43 Posts
Hi,

no, the more octane the better the engine will run and the less it will consume
as the fuel efficiency is getting better.

so, your engine will say, thank you.
here we only have 91 to 100 octane gas in europe.
 

·
Registered
Joined
·
94 Posts
Hi,

no, the more octane the better the engine will run and the less it will consume
as the fuel efficiency is getting better.

so, your engine will say, thank you.
here we only have 91 to 100 octane gas in europe.
Thanks!
 

·
Registered
Ram 1500
Joined
·
854 Posts
Hi,

no, the more octane the better the engine will run and the less it will consume
as the fuel efficiency is getting better.

so, your engine will say, thank you.
here we only have 91 to 100 octane gas in europe.
Completely and utterly false. The only way that would be true is if the timing can be advanced to take advantage of the increased octane, if the timing isn't increased you are not doing your engine any favors.

As a example, I run 87 octane in my fusion every time, a few months after I bought it I decided to try 91 octane to see if it would help anything. To this day that is the worst fuel economy I have ever seen out of that car. I went from getting 26ish to 22-23.
 

·
Registered
Joined
·
43 Posts
maybe on your fusion it is not working, as it has a rubbish engine inside :)

but modern engines check automatically what kind of octane they get and know
how to handle.

and the v8 hemi is the same engine running in the usa and in europe.
here it is recommended to use them with 95 or 98 octane
and it will definetely need more gas when running with only 87 octane.

even nearly ALL high performance cars need to use 98 to 100 octance gas,
what do you think why ?!? ... as only with this gas the engines can get the
maximum power out of it.

and this is much better gas then to go with only 87.

it is like that. !!!
 

·
Registered
Ram 1500
Joined
·
854 Posts
maybe on your fusion it is not working, as it has a rubbish engine inside :)

but modern engines check automatically what kind of octane they get and know
how to handle.

and the v8 hemi is the same engine running in the usa and in europe.
here it is recommended to use them with 95 or 98 octane
and it will definetely need more gas when running with only 87 octane.

even nearly ALL high performance cars need to use 98 to 100 octance gas,
what do you think why ?!? ... as only with this gas the engines can get the
maximum power out of it.

and this is much better gas then to go with only 87.

it is like that. !!!
I believe step one is the fact you are in Europe. If I remember right you guys measure octane different over there.

High performance cars do require higher octane gas because they are designed for it, not to insult anyone here but the 5.7 hemi is by no means a high performance engine. It will not take advantage of the higher octane. It doesn't sense what octane you have in the tank it will just run as much advance as is in the timing map until it detects detonation, then it will start pulling timing until it goes away, then start adding timing until detonation starts again and keeps going back and forth until it finds where the detonation is and runs the timing there. If you add some sort of programmer then sure if you have the 91 or 93 octane tune you should be running that, if not you are just throwing money away. For the record it wasn't just my fusion I have done this to, every vehicle I have owned I try it, same thing every time.
 

·
Registered
Joined
·
43 Posts
maybe we do measure it different .... but that huge difference. ?!?
... but thanks for the information, good to know.

but quite poor for an engine built in 2013 ... not having these standard features on board.

would be more easy if there would be one world standard at all :)
 

·
Registered
Joined
·
941 Posts
maybe we do measure it different .... but that huge difference. ?!?
... but thanks for the information, good to know.

but quite poor for an engine built in 2013 ... not having these standard features on board.

would be more easy if there would be one world standard at all :)
You do, and it is quite different.

Running high test in a Hemi will do you no good, it's calibrated for 87/89. If you use 89 it ill run at normal timing and prove slightly more power. If you run 87 it will pull timing and slightly reduce power. If you run 91 you will only get the effect that the 89 had, and it may interfere with the MDS system (based on reports on the boars here, not sure how accurate that is so take it with a grain of salt).

We still have to get a lot of Europe to drive on the right side of the road before we even think about measuring octane the same way.
 

·
Super Moderator
Joined
·
9,315 Posts
Hi,

no, the more octane the better the engine will run and the less it will consume
as the fuel efficiency is getting better.

so, your engine will say, thank you.
here we only have 91 to 100 octane gas in europe.
Nope. Not at all. And it's a waste of money. Octane calculations are different here, too. We have typically 87, 89 and 91 derived by the specific formula used in North America.

Higher octane burns slower and is used in engines that require that the fuel not light off prematurely from things like higher compression. ("knocking") It provides zero benefit for engines that don't require it. The Hemi V8 in the GGC will run "best" with 89 octane (US calculation) but runs just great on 87. The manufacturer indicates that 87 is acceptable in the manual. The computer compensates for this automatically. To-date, I've only put 89 in one time and that was accidentally...really...I picked up the wrong nozzle and was filled before I noticed. :eek:
 

·
Registered
Joined
·
43 Posts
ok, i got it ... and many thanks for the lessons :)

... but interesting anyway.
 

·
Registered
Joined
·
57 Posts
Slightly less hp are the implications. The vehicle is smart enough to sense that it has 87 in it, and will pulling timing back to compensate. This yields a slight (15ish?) loss in hp.

People will tell you that its better to use 89 long term for a variety of (mostly bogus) reasons. Keep in mind, the Hemi is also a work truck engine, and can run for hundreds of thousands of miles on 87.

Sometimes I feel like I get slightly better fuel economy using 89. It may be a psychological thing though.
I dont think it is psychological. Compression Ratio has a huge impact on the otto efficiency of an engine. The compression ration doesnt change, but the advance of the spark is effectively a dynamic change to compression ratio and hence increases efficiency... Efficiency is a double edged sword in that more power normally makes the right foot put more of a grin on your dial... but that efficiency (all things being equal) will also give better economy. The knock sensors will advance the ignition in a vehicle like this and you will see economy increases... We get 91 standard octane, 95 and 98 octane in Oz. You do measure Octane via RON, dont you in the US?
 

·
Registered
Joined
·
57 Posts
Readin further on here... If the overseas versions do not advance to the point that they will take advantage of higher octanes (RON ratings) then you wont see the advantages... Makes me think that a tune in Aust will make a huge difference to the output figures if I run 98 Octane.

Why is it that America runs all its measurements different to the rest of the planet? You guys do realise that there are a lot more people on this planet that do agree to a "Standard International" (SI) setof units... Even the Poms cant agree though, they have their own Gallon... LOL! At least we speak the same language... mainly!
 
1 - 20 of 37 Posts
Top